Covalent Functionalization by Cycloaddition Reactions of Pristine Defect-Free Graphene
2017 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 1, 627-634 p.Article in journal (Refereed) Published
Based on a low-temperature scanning tunneling microscopy study, we present a direct visualization of a cycloaddition reaction performed for some specific fluorinated maleimide molecules deposited on graphene. Up to now, it was widely admitted that such a cycloaddition reaction can not happen without pre-existing defects. However, our study shows that the cycloaddition reaction can be carried out on a defect-free basal graphene plane at room temperature. In the course of covalently grafting the molecules to graphene, the sp(2) conjugation of carbon atoms was broken, and local sp(3) bonds were created. The grafted molecules perturbed the graphene lattice, generating a standing-wave pattern with an anisotropy which was attributed to a (1,2) cycloaddition, as revealed by T-matrix approximation calculations. DFT calculations showed that while both (1,4) and (1,2) cycloadditions were possible on free-standing graphene, only the (1,2) cycloaddition could be obtained for graphene on SiC(0001). Globally averaging spectroscopic techniques, XPS and ARPES, were used to determine the modification in the elemental composition of the samples induced by the reaction, indicating an opening of an electronic gap in graphene.
Place, publisher, year, edition, pages
2017. Vol. 11, no 1, 627-634 p.
graphene functionalization, covalent grafting, maleimide molecule, UV and X-ray photoemission, scanning tunneling microscopy, Raman spectroscopy
IdentifiersURN: urn:nbn:se:uu:diva-316952DOI: 10.1021/acsnano.6b06913ISI: 000392886500064PubMedID: 28027437OAI: oai:DiVA.org:uu-316952DiVA: diva2:1079543
FunderEU, European Research Council, NANOGRAPHENE 256965